Plans to expand Attica motorway to eight lanes and upgrade key interchanges

The most significant proposed intervention concerns the addition of two lanes along the 6.3-kilometre section between Penteli and Metamorfosi, where the existing six lanes are planned to be increased to eight, with four lanes in each direction. However, the widening works are subject to technical constraints due to the presence of bridges, retaining walls and other structures.

The new standard cross-section provides for an emergency stopping lane (hard shoulder) with a width of 2.50 metres. At certain locations, however, where sufficient space is unavailable, the hard shoulder will be eliminated.

These locations are primarily situated near infrastructure such as Kifisias Avenue, the ISAP railway line and Irakliou Avenue, where the demolition or reconstruction of existing engineering structures would result in significant traffic disruptions.

At these locations, emergency stopping bays, enhanced road markings, rumble strips and speed restrictions are proposed. According to the study, the maximum distance without a hard shoulder, exit or emergency stopping bay will be approximately 500 metres.

From Six to Eight Lanes Along the Penteli–Metamorfosi Section

The most significant intervention concerns the central section of the Attica Motorway, extending between the Penteli Avenue interchange and the eastern access to the Metamorfosi interchange.

Along this 6.3-kilometre section, one additional lane is planned in each direction, thereby increasing the overall traffic capacity of the motorway.

The intervention aims to address daily traffic congestion, which is particularly severe during peak hours, resulting in significantly reduced speeds and increased journey times.

Third Lane in Pallini

In the area of the Pallini grade-separated interchange, along Marathonos Avenue, the widening of a 1.3-kilometre section is being considered. The intervention предусматри the addition of one lane in each direction, increasing the existing two lanes to three. The operational width of the motorway will increase from 11.10 to 13.25 metres in each direction.

This particular area frequently experiences traffic congestion, characterised by low vehicle speeds and the formation of long queues.

Two New U-turn Connections at the Leontari Interchange

Further widening works are being considered in the Pallini interchange area, while additional interventions are planned along the Western Hymettus Ring Road and at the Leontari interchange, with the aim of addressing traffic congestion and improving connections to the Airport and Eastern Attica.

The study includes the construction of two new U-turn connections, which will facilitate traffic movements that are not currently served by direct connections.

The first will serve traffic movements between Markopoulo and Rafina in both directions. It will be constructed west of the interchange, between Solomou and Kazantzakis Streets, and will comprise a 437-metre connecting road and a bridge approximately 100 metres long.

The second will serve traffic movements between Elefsina and Alimos/Katechaki Avenue in both directions. It is planned east of the interchange and will comprise a 355-metre connecting road and a 147.3-metre-long bridge.

The decision to opt for U-turn connections rather than new direct three-level connecting ramps is attributed to space constraints and the higher cost associated with alternative solutions. In parallel, a third lane is planned along the section extending from the Leontari interchange towards the Pallini interchange.

Dual-Lane Entry from the Hymettus Ring Road

The proposed interventions also include the redesign of the entry ramp connecting the Western Hymettus Ring Road to the Attica Motorway in the direction of Elefsina. The ramp is planned to accommodate two entry lanes, with the aim of increasing traffic capacity at the merging point.

The intervention extends approximately 150 metres before the junction and 350 metres within the underground section of the Attica Motorway. Due to existing technical constraints, a speed limit of 50 km/h and an emergency stopping bay approximately 50 metres long are proposed.

Tunnel Improvements and Road Safety Measures

In addition to the widening works, the environmental assessment includes interventions aimed at improving motorway safety. These include the replacement of existing metal safety barriers with new vehicle restraint systems compliant with European Standard EN 1317, as well as the construction of a new pedestrian emergency exit in the Vrilissia Tunnel, on the carriageway towards the Airport.

The tunnel is 940 metres long and currently has no intermediate emergency exit. The proposed installation aims to improve evacuation conditions in the event of a fire or other serious incident.

Environmental Protection and Energy Efficiency Improvements

The study also provides for the construction of four pollution control units designed to prevent oils, petroleum products and other pollutants from being discharged from the road surface into natural water bodies. Two units are proposed in the Rafina stream area and two within the Erasinos river catchment, in the wider Vravrona area.

At the same time, the replacement of lighting systems along open motorway sections and inside tunnels with LED technology is being considered, with the aim of reducing energy consumption and maintenance requirements.

The programme also includes the upgrading of snow-clearing facilities and the establishment of a new central salt storage facility at the Aspropyrgos Motorists’ Service Station. Following the proposed interventions, the total potential salt storage capacity will reach 3,650 tonnes.

Furthermore, the installation of two fuel storage tanks, each with a capacity of 25 cubic metres, is planned in Paiania and Roupaki, with the aim of enhancing the operational autonomy of service vehicles.

How the Construction Works Will Be Carried Out

The study also outlines the proposed traffic management arrangements during the implementation of the motorway widening works.

Along the Penteli–Metamorfosi section, three lanes in each direction are expected to remain operational, with traffic initially diverted towards the central reservation and subsequently towards the outer side of the motorway.

In Pallini, two lanes in each direction will remain available, while traffic along the Hymettus Ring Road ramp will be accommodated by a single lane during the main construction phases.

These traffic management arrangements constitute proposals included in the study and do not represent a formally approved final construction programme.